On 08/21/2018 04:08 PM, Alexander Graf wrote:
On 08/21/2018 03:57 PM, Marc Zyngier wrote:
On 21/08/18 14:35, Alexander Graf wrote:
On 10/23/2017 06:11 PM, Marc Zyngier wrote:
The only case where we actually need to perform a dcache maintenance
is when we map the page for the first time, and subsequent permission
faults do not require cache maintenance. Let's make it conditional
on not being a permission fault (and thus a translation fault).
Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
This patch unfortunately breaks something on Hi1616 SoCs when running
32bit guests. With this patch applied (and thus with 4.18) I get random
illegal instruction warnings from 32bit code inside VMs. I do not know
at this point whether this affects other CPUs as well.
Can you please give a few more details?
- what are the CPUs on this Hi1616? At least a /proc/cpuinfo would help
These are A72s:
processor : 0
BogoMIPS : 100.00
Features : fp asimd evtstrm aes pmull sha1 sha2 crc32 cpuid
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x0
CPU part : 0xd08
CPU revision : 2
- an example of the crash? Is it within the decompressor? After? This
things do matter, given the number of crazy things the 32bit kernel does
They are always in user space. My current reproducer is this:
$ while rpm -qa > /dev/null; do :; done
If I run this in parallel with something that just populates RAM (dd
if=/dev/nvme0n1 of=/dev/null bs=10G) I get an illegal instruction
fault within seconds:
sh-4.4# while rpm -qa > /dev/null; do true; done
Illegal instruction (core dumped)
- a host kernel configuration?
Host kernel configuration is just the normal openSUSE one:
https://kernel.opensuse.org/cgit/kernel-source/plain/config/arm64/default?h=stable
If anyone is interested in a reproducer, I have something handy. But
for
now I believe we should just revert this patch.
Before we revert anything, I'd like to understand what is happening.
Yeah, I didn't realize the commit is already in since 4.16, so I
agree. I'll bisect a bit, but it may take a while.
I'm stuck on bisect. Somewhere in the merge window things broke so badly
that udev just segfaults on boot. I got this far:
$ git bisect log
git bisect start
# good: [29dcea88779c856c7dc92040a0c01233263101d4] Linux 4.17
git bisect good 29dcea88779c856c7dc92040a0c01233263101d4
# bad: [529bea37411759c2b5b41a187b3020723c67c16d] Linux 4.18.1
git bisect bad 529bea37411759c2b5b41a187b3020723c67c16d
# good: [3036bc45364f98515a2c446d7fac2c34dcfbeff4] Merge tag
'media/v4.18-2' of
git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
git bisect good 3036bc45364f98515a2c446d7fac2c34dcfbeff4
# good: [721afaa2aeb860067decdddadc84ed16f42f2048] Merge tag 'armsoc-dt'
of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
git bisect good 721afaa2aeb860067decdddadc84ed16f42f2048
# good: [e7441c9274a6a5453e06f4c2b8b5f72eca0a3f17] mac80211: disable
BHs/preemption in ieee80211_tx_control_port()
git bisect good e7441c9274a6a5453e06f4c2b8b5f72eca0a3f17
# bad: [05df204549c510c7c56e58d25098c448998a0cd5] Merge tag
'devicetree-fixes-for-4.18' of
git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
git bisect bad 05df204549c510c7c56e58d25098c448998a0cd5
# good: [b19b9282093588e73401f9d4981310a8de975f7d] Merge tag
'riscv-for-linus-4.18-rc4' of
git://git.kernel.org/pub/scm/linux/kernel/git/palmer/riscv-linux
git bisect good b19b9282093588e73401f9d4981310a8de975f7d
# good: [bf642e3a1996f1ed8f083c5ecd4b51270a9e11bc] Merge tag
'drm-intel-fixes-2018-07-12' of
git://anongit.freedesktop.org/drm/drm-intel into drm-fixes
git bisect good bf642e3a1996f1ed8f083c5ecd4b51270a9e11bc
# bad: [2a7e1211e130c51a2b5743ecf247645ac8e936ee] Merge tag
'vfio-v4.18-rc5' of git://github.com/awilliam/linux-vfio
git bisect bad 2a7e1211e130c51a2b5743ecf247645ac8e936ee
# bad: [a74aa9676c0256eac05efb2c8e3127e0835e66e5] Merge tag
'char-misc-4.18-rc5' of
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
git bisect bad a74aa9676c0256eac05efb2c8e3127e0835e66e5
# bad: [f1454959ad89f9fe2b6862fa3c41070feaffeab9] Merge tag
'mmc-v4.18-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc
git bisect bad f1454959ad89f9fe2b6862fa3c41070feaffeab9
# bad: [1e09177acae32a61586af26d83ca5ef591cdcaf5] Merge tag
'mips_fixes_4.18_3' of
git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux
git bisect bad 1e09177acae32a61586af26d83ca5ef591cdcaf5
# good: [4f65245f2d178b9cba48350620d76faa4a098841] HID: hiddev: fix
potential Spectre v1
git bisect good 4f65245f2d178b9cba48350620d76faa4a098841
Alex
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